Caterpillar-tread.



JOHN FBOELIC'H, OIF-ST. PAUL, MINNESOTA.

CATERPILLAR-T1msn.

Specification ot Letters Patent.

Patented Oct. 22, 1918.

Application me@ June 24, 1914. Serial No. 847,005.

y'To all whom it mag coneernl' at I, JOHN FRoELIcH, a citizen of the United States, residin at St..V Paul, in the county of RamseyA and 'State of Minnesota, have invented new and useful Im rovements in Caterpillar-Treads, 4of whlch the followin is a specification.

My invention re ates to cast metal treads Be it known t -for what are known as caterpillar tractors,

superposed rollers, thereby sometimes breaking off the roller spindles. This necessitates repair, and `meanwhile decreases, the tracve power of the vehicle.

`hc object of my invention is to make the series of tread units self sustaining, and this object is effected by the peculiar and novel :onstruction `of each tread unit, hereinafter described and claimed.

Referring to the accompanying drawings, `igure 1 1s a perspective of a tread unit instructed according to the invention, owed from its inner side; Fig.' 2-is a side alvation-of two of the tread units in asicnbled relation; Fig. 3 is a plan view of 2h@ tread face of a tread unit; Fig. 4 is a :ettional view on a line 4--4 of Fig. 3; and *"ig, 5 is a diagram showing the manner in vhskh two associated treads may be sepa- 'ate Each of the treads or tread units herein hown is cast in oneV piece and all are pre- :iselv alike.l so that a description of one .pnlies to all. y I

I n general, each tread unit may be said to ornprise a base or body portion 10, a tread late 11 and a pair of webs 12 that unite he base and tread portions. The body :ierges into the inner portion of the webs 12 nd includes (as` shown three) transverse ibs 1l having, inclined lateral faces 14* rhich provide suitable slots 15 to receive he teeth of the usual toothed driving wheels f acaterpillartractor. The linner face of' he base 10 is'flat, as clearly shown on Fig. The tread plate 11 is rectan lar in' outne, as shown by Fig. 3, and as a. transverse concai'ity 13 in its outer face. The webs 12 are spaced, as shown, and there is a hollow 16 between the tread plate 11 and base 10, which hollow lightens the casting without reducing its strength. i

Integral with one end of each web 12 is a heavy rib 17 extending from the inner to the outer face ofthe tread and each rib 17 merges into a boss 18 in which is a cylindrical socket 19, open at both ends and also at its bottom. Each socket has a portion of its wall cut awav at right angles to the line of travel, es shown at 20, for a reason presently set forth. The sockets 19 at the two ends of the tread are duplicates, and are in alinement with each other.

Each'of-the webs 12 is provided upon its inner corner, opposite the socket 19, with a pintle 21 which is. dimensioned to fit pivotally within'a socket of the next tread in the chain, as shown on Fig. 2. rEach pintle 21 is cut away at 22, in the general plane of the base. In other words, each stud 21 is cut away upon the chord of`a circle and in the plane of travel of the tread. The reduction in diameter thus effected is only ,'suiicient to permit the studs to be removed from their sockets 19 when necessary, and this is done bv firstiturning the two treads (marked a and b on Fig. 5) from their normal relation to a right angled relation. and. disengaging the tread b in the direction of the arrow. Normally, however, it will be impossible for anv tread to become-detached from the mres, because the lips23 of the sockets 19 embrace a suflicient part of the studs 21 to prevent;- this.

Each tread plate 11 is provided on one side thereof with a part 24 hereinafter termed a flange or abutment fiange. The flange 24 of each tread plate is adapted to overlap the surface 25 of an adjacent tread plate. The surface 25 is depressed (as 'shown)'to,form a shoulder 26 which abuts the outer edge 24l of fiange 24 when two connected treads are in alinement as they will be at the top and bottom of the chain, on the tractor wheelsi The surface 25 is shown as convex with its center of curvature at the center of the pintle 21. The

inner face 24" of, flange 24 is corerspondinglycurved.

Considerin a horizontal series oftreads connecting t e upper sides of the drivewheels (a .ortion of such a series being shown by ig. 2) it is evident that the weight of the parts will tend to cause the".

upwardly, hence it will act as a substantially' straight beam and will support the wheels and frame of the tractor. When running on flat ground, this property of the tread chain or series obviates the use of depression rollers or guides, and causes each tread unit to exert downward pressure as if such depression guides were employed.

' In order to reduce the occasionally heavy stress on the treads, it is thought desirable `to provideeach tread with auxiliary abut ments which will coact simultaneously with the abutments above described. One form of such provision is shown on Figs. 1 and 2, wherein 27 is a heavy lug which projects from the rib-l7 and is located at the inner side of thetread.' A. coacting nose-shaped abutment 28- is formed on the opposite side of the pivot socket and continues outwardly as a rib 29 which is in fact a thickening of the end web 30, the latter being an extension of the. main web l2 but, as shown on Fig. '1, thicker than web 12.

An endless chain of the treads described may be assembled in the manner indicated by Fig. 5, and such a chain will be self-supporting at both top and bottom, as has a1- ready been shown. This construction will greatly reduce the cost of tractors of the type referred to, and has additional advantages because of the reduction in the number of wearing parts and of parts liable to breakage.

Having described my invention, what I claim as new and desire to protect by .Letters Patent, is:

1. In a caterpillar tread, a series of tread units, each comprising a base and treadv plate,l a web between said base and tread plate, pivots at one end of the base and sockets at the other end designed to receive the pivots of a contiguous tread unit, said tread plate being provided with a transverse ange at one end and a recess at the opposite end, said recess being adapted to re ceive a like flange on the adjacent tread unit, the lower side of said flange and the bottom of said recess conforming respectively with arcs struck from the axis of the pivots and the center of the sockets.

2. In a tread a plurality of connected similar tread units, said tread units having pivotal connections integral ,therewith to permit the bending of the tread in one direction and also having coperating devices integral with said tread units to prevent the bending of the tread in the opposite'direction, each of said pivotal connections comprising a male and female member, said members being normally self-retaining but f being adapted to permit 'separation of two adjacent units when said units are turned to a certain-relative angle upon their pivots.

3. In a tread, a plurality of connected similar tread units, said tread units having pivotal connections to permit the bending of the tread in one direct-ion and also having coperating devices to prevent the bending of said tread in the opposite direction, said oo erating devices comprising a transverse rabget adjacent the tread surface of the unit and having a convex wall, and transverse abutments coperating respectively with, a' transverse flange and medial lugs formed on the opposite end of each tread unit in the series, each of said units being provided with a pintle and with a pintle-receiving socket,.the pintle of one unit being revolubly inserted inthe socket of the other unit, each pintle having a flat side and each socke aving an open sidewhich is of sufeien Width to permit lateral insertion or with drawal of a pintle when the two units con cerned are turned to a certain relative ang'll.

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.

JOHN FRoELIoH.

Witnesses z F. C. CASWELL, MAE BEAMER. 

